The location of the configuration file is set in WEB-INF/geowebcache-core-context.xml. If you wish to set a different location for the configuration file, open geowebcache-core-context.xml and look for the <bean> tag referencing gwcXmlConfig:

Uncomment the bottom <constructor-argvalue=...> tag and specify the location where you would like to place geowebcache.xml.

Editing the configuration file by hand can be tricky, since the smallest typo may cause GeoWebCache to stop functioning. Furthermore, The order of the XML elements is crucial!

It is recommended to use a special XML editing tool or at the very least a text editor with syntax highlighting. Furthermore, using an editor with XML schema validation will tell you right away if you are missing a tag or have placed elements out of order.

Two recommended free editors, both of which have support for XML validation, are:

All configuration options and parameters are ultimately located in the XML schema. While the documentation you are reading now is designed to translate and interpret the schema to make the GeoWebCache configuration simpler, expert users can look at the schema to determine all details, including variable types, ordering of elements and much more.